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Vulnerability record · CVE-2020-11053 · published 7 May 2020

CVE-2020-11053: Oauth2 proxy project oauth2 proxy open redirect vulnerability

OOauth2 Proxy Project · Oauth2 Proxy

In OAuth2 Proxy before 5.1.1, there is an open redirect vulnerability. Users can provide a redirect address for the proxy to send the authenticated user to at the end of the authentication flow. This is expected to be the original URL that the user was trying to access. This redirect URL is checked within the proxy and validated before redirecting the user to prevent malicious actors providing redirects to potentially harmful sites. However, by crafting a redirect URL with HTML encoded whitespace characters the validation could be bypassed and allow a redirect to any URL provided. This has been patched in 5.1.1.

6.1 CVSS 3.1 Medium EPSS 0.79% · top 45.5% CWE-601 · Open redirect
6.1CVSS 3.1 base score, v2 5.8
0.79%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References
17 Jun 2026Last modified by NVD

Description

In OAuth2 Proxy before 5.1.1, there is an open redirect vulnerability. Users can provide a redirect address for the proxy to send the authenticated user to at the end of the authentication flow. This is expected to be the original URL that the user was trying to access. This redirect URL is checked within the proxy and validated before redirecting the user to prevent malicious actors providing redirects to potentially harmful sites. However, by crafting a redirect URL with HTML encoded whitespace characters the validation could be bypassed and allow a redirect to any URL provided. This has been patched in 5.1.1.

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/oauth2-proxy/oauth2-proxy/security/advisories/GHSA-j7px-6hwj-hpjg Vendor Advisory
https://github.com/oauth2-proxy/oauth2-proxy/security/advisories/GHSA-j7px-6hwj-hpjg Vendor Advisory

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Source: NIST National Vulnerability Database (record CVE-2020-11053), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.